1. Field of the Invention
The invention relates to a device for producing thin boards by chip-free slicing separation of the boards from timber comprising a log or cant and, in particular, to means for feeding the cants in such device.
2. Description of Related Art
German Published Application 37 02 909 and the same applicant's corresponding European Published Application 0277591 and corresponding U.S. Pat. No. 4,825,917, the entire disclosures of which are hereby incorporated by reference disclose a device for the production of thin boards by the chip-free slicing removal of the boards from a log or cant, with a feed path for the cant, a slicing device located at one side of the feed path, a fixed or vibratable slicing blade for severing a board and a counterpressure rail, mounted before the cutting blade. The spacing of the counterpressure rail from the cutting blade, transverse to the feed path of the cant, substantially determines the thickness of the board to be removed and the counterpressure rail is part of a support table for the cant, which table is optionally adjustable in height relative to the blade. The cutting blade and the counterpressure rail subtend an acute angle with the feed path of the cant and a pressing device lies opposite the slicing device at the other side of the feed path and can be pressed against the cant and, thus, the opposed slicing device. Feed rollers are provided for feeding the cant to the cutting blade of the slicing device along the feed path, at least one pair of the feed rollers engaging the cant at opposite sides and clamping the cant therebetween.
In the slicing of boards from a cant, the production of the boards depends on a satisfactory guidance of the cant along the blade. Comparatively high forces are employed for the feeding of the cant relative to the blade, which are applied for example by the feed rollers, which are pressed hard against the cant, the feed rollers being located before and/or after the actual slicing device through which the cant travels.
The forces exerted by the feed rollers on the cant should not adversely affect the satisfactory guiding of the cant in the slicing to the blade, and therefore it was already proposed, in the above-mentioned German Published Application 37 02 909, to journal the feed rollers in pairs floating in the direction transverse to the feed direction of the cants, so that a pair of feed rollers can exert a high clamping force on the cant, which clamping force, however, does not exert any harmful affect on the cant. By these means, it should be ensured that, during the cutting, the pressing of the cant against the blade and the counterpressure rail associated therewith can be adjusted to and maintained at the required level without adversely affecting the feed forces.
During the slicing separation of a cant into thin boards, which are for example further processed into solid wood laminated products, it is desirable to separate a cant completely into such thin boards without an off-size remnant, which is not further processable, being left over. It has now been found that, for a remnant cant, from which several boards have already been removed, the optimum cutting conditions at the blade can not be accurately maintained, despite the feed rollers which are arranged before and after the actual slicing device and which are floatingly supported. This is possibly a consequence of the fact that a previously extensively processed cant no longer possesses sufficient stability to absorb the feed forces in such a manner that they do not affect the slicing region.